- Cold Start:
- In order to be classified as a cold start, the engine coolant temperature must be below 122 °F (50 °C) and within 11 °F (6 °C) of the ambient air temperature at startup.
- Do not leave the key on prior to the cold start, or the heated oxygen sensor diagnostic may not run.
- Idle:
- The engine must be run for two and a half minutes with the air conditioner on and rear defroster on, the more electrical load you can apply the better.
- This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
- Accelerate:
- Turn off the air conditioner and all the other loads, and apply half throttle until 55mph (88km/hr) is reached.
- During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
- Hold Steady Speed:
- Hold a steady speed of 55mph (88km/hr) for 3 minutes.
- During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
- Decelerate:
- Let off the accelerator pedal. Do not shift, or touch the brake or clutch.
- It is important to let the vehicle coast along gradually slowing down to 20 mph (32km/hr).
- During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
- Accelerate:
- Accelerate at 3/4 throttle until 55-60mph (88-96 km/hr).
- This will perform the same diagnostics as in step 3.
- Hold Steady Speed:
- Hold a steady speed of 55mph (88km/hr) for five minutes, which I know is hard to do.
- During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed.
- If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
- Decelerate:
- This will perform the same diagnostics as in step 5.
- Again, don't press the clutch or brakes or shift gears.
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© Gary Sullivan
Maintainer of this page. |
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